A drill string consists of a plurality of threadably connected joints of drill pipe, wherein each drill pipe has a length of approximately thirty feet long. One end of each drill pipe has internal threads (the “box” end of the pipe), and an opposite end of each drill pipe has external threads (the “pin” end of the pipe). A series of three threadingly connected drill pipes is commonly referred to as a “stand” of drill pipe. Each stand has a length of approximately 90 feet. Multiple stands of ready to use drill pipe are typically stored vertically supported by the drill floor and restrained in an assembly commonly referred to as a fingerboard.
A top drive well drilling apparatus typically includes a top drive system (TDS). The TDS includes a tubular main shaft, a lower end of which is threadingly connectable to an upper end of a drill string. The TDS drives the drill string rotatively and moves upwardly and downwardly with the drill string during a drilling operation. The TDS includes a motor to drive the main shaft, and therefore the drill string, during a drilling operation. The TDS includes an assembly for receiving drilling fluid. During the drilling operation, the drilling fluid (commonly referred to as “drilling mud”, or simply “mud”) is pumped through the TDS to the drill string and down to the drill bit to provide lubricity to the drill bit, thereby facilitating the drilling operation. However, during drilling drill bit cuttings, shavings and other abrasive articles (hereinafter referred to as waste products) accumulate in the drilling mud. The waste products can cause extensive wear to the interior surfaces of the drill string and the drill bit and to drilling parameter measuring devices. Consequently it is desirable to filter the drilling mud to remove the accumulated waste products.
In conventional filtration systems a mud filter or screen is inserted into the box end of a stand of drill pipe that is to be attached to the drill string. However, in order to insert the filter an oil well operator (commonly referred to as a “roughneck”) must be lifted the approximately 90 feet to the top of the stand of drill pipe. This is typically accomplished by placing the roughneck in an apparatus called a riding belt. This procedure is very dangerous, and produces an undesirably high risk of serious injury or death to the roughneck.
Accordingly, there is a need for an improved method and device for filtering drilling mud in an oil or gas well drilling system that does not create a risk of injury to the roughneck.